Open or damaged control wire between the PCM and ignition coil H, often from chafing or a broken connector pin; Failed ignition coil H with an open internal primary winding or driver circuit; Corroded, loose, or water-intruded electrical connector at coil H or at the PCM; Short to voltage on the control circuit, such as a rubbed-through wire touching a power feed; PCM driver failure for that specific coil control channel, though this is less common; Aftermarket alarm or remote-start wiring that has tapped into or disturbed the coil control circuit

DTC codes / P03xx · Ignition system and misfire / P036F

P036FIgnition H Control Signal Circuit High

Q: What does code P036F mean?

Ignition H Control Signal Circuit High. P036F indicates that the powertrain control module (PCM) has detected an abnormally high voltage on the control circuit for ignition coil H, which is one of the individual coil-on-plug or coil-per-cylinder circuits. The PCM commands a ground to fire the coil, so a high-voltage reading on the control wire tells the module that the circuit is open, shorted to voltage, or that the coil's internal driver has failed.

P036F indicates that the powertrain control module (PCM) has detected an abnormally high voltage on the control circuit for ignition coil H, which is one of the individual coil-on-plug or coil-per-cylinder circuits. The PCM commands a ground to fire the coil, so a high-voltage reading on the control wire tells the module that the circuit is open, shorted to voltage, or that the coil's internal driver has failed.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaIgnition system and misfire

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
Rough idle or misfire felt as shaking or a stumble, especially when the engine is cold
Reduced engine power or a limp-home mode if the fault is severe enough to trigger protection strategies
Poor fuel economy or a strong raw-fuel smell from the exhaust
Occasional hard starting or a crank-no-start condition if the affected cylinder is critical
A flashing check engine light under load, indicating a misfire that can damage the catalytic converter

Common causes, most likely first

Open or damaged control wire between the PCM and ignition coil H, often from chafing or a broken connector pin
Failed ignition coil H with an open internal primary winding or driver circuit
Corroded, loose, or water-intruded electrical connector at coil H or at the PCM
Short to voltage on the control circuit, such as a rubbed-through wire touching a power feed
PCM driver failure for that specific coil control channel, though this is less common
Aftermarket alarm or remote-start wiring that has tapped into or disturbed the coil control circuit

How to diagnose and fix it

Scan all modules and record freeze-frame data to confirm P036F is active and not a history code from a past repair
Inspect the ignition coil H connector and the PCM connector for corrosion, loose pins, or pushed-out terminals
Swap ignition coil H with a known-good coil from another cylinder and see if the code follows the coil or stays with the cylinder
Use a digital multimeter to check the control circuit for an open, a short to ground, and a short to voltage with the PCM disconnected
Back-probe the control wire with a lab scope or a noid light to verify the PCM is actually commanding the coil to fire
Repair or replace the faulty section of harness, the connector, or the coil as indicated by the tests
Clear the code and perform a road test with a scan tool to confirm the repair and that no misfire counters return

Why coil H control faults get misdiagnosed

A high-voltage control signal code does not automatically mean the coil is bad; an open control wire or a poor connector pin will set the same code and replacing the coil will not fix it.
Technicians often overlook that the PCM fires the coil by grounding the control circuit, so a high voltage reading can simply mean the PCM is not commanding the coil at all due to a driver fault or a wiring break.
Water intrusion into the coil connector or a cracked coil boot can cause intermittent high-voltage readings that only appear in damp weather, leading to a no-fault-found diagnosis.
Aftermarket remote starters and alarm systems frequently splice into ignition coil control wiring, and a poor splice can create the high resistance that sets P036F.
A misfire from a failed coil H can damage the catalytic converter quickly, so a flashing check engine light should be treated as an urgent stop-driving condition even if the code seems minor.

Can I keep driving with P036F?

You can usually drive a short distance to a repair shop if the check engine light is steady and the engine runs smoothly, but avoid heavy acceleration and towing. If the light is flashing or the engine is misfiring badly, stop driving to prevent catalytic converter damage.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.